linux-hardening - Re: [PATCH v3 2/6] mm/slab: Plumb kmem_buckets into __do_kmalloc

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Message-ID: <fb2227dc-facb-4760-ba91-49abb54a991c@suse.cz>
Date: Fri, 24 May 2024 15:38:58 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Kees Cook <keescook@...omium.org>
Cc: Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
 David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
 linux-hardening@...r.kernel.org, "GONG, Ruiqi" <gongruiqi@...weicloud.com>,
 Xiu Jianfeng <xiujianfeng@...wei.com>, Suren Baghdasaryan
 <surenb@...gle.com>, Kent Overstreet <kent.overstreet@...ux.dev>,
 Jann Horn <jannh@...gle.com>, Matteo Rizzo <matteorizzo@...gle.com>,
 Thomas Graf <tgraf@...g.ch>, Herbert Xu <herbert@...dor.apana.org.au>,
 julien.voisin@...tri.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/6] mm/slab: Plumb kmem_buckets into
 __do_kmalloc_node()

On 4/24/24 11:40 PM, Kees Cook wrote:
> To be able to choose which buckets to allocate from, make the buckets
> available to the lower level kmalloc interfaces by adding them as the
> first argument. Where the bucket is not available, pass NULL, which means
> "use the default system kmalloc bucket set" (the prior existing behavior),
> as implemented in kmalloc_slab().
> 
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Christoph Lameter <cl@...ux.com>
> Cc: Pekka Enberg <penberg@...nel.org>
> Cc: David Rientjes <rientjes@...gle.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Roman Gushchin <roman.gushchin@...ux.dev>
> Cc: Hyeonggon Yoo <42.hyeyoo@...il.com>
> Cc: linux-mm@...ck.org
> Cc: linux-hardening@...r.kernel.org
> ---
>  include/linux/slab.h | 16 ++++++++--------
>  lib/fortify_kunit.c  |  2 +-
>  mm/slab.h            |  6 ++++--
>  mm/slab_common.c     |  4 ++--
>  mm/slub.c            | 14 +++++++-------
>  mm/util.c            |  2 +-
>  6 files changed, 23 insertions(+), 21 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index c8164d5db420..07373b680894 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -569,8 +569,8 @@ static __always_inline void kfree_bulk(size_t size, void **p)
>  	kmem_cache_free_bulk(NULL, size, p);
>  }
>  
> -void *__kmalloc_node_noprof(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment
> -							 __alloc_size(1);
> +void *__kmalloc_node_noprof(kmem_buckets *b, size_t size, gfp_t flags, int node)
> +				__assume_kmalloc_alignment __alloc_size(2);
>  #define __kmalloc_node(...)			alloc_hooks(__kmalloc_node_noprof(__VA_ARGS__))
>  
>  void *kmem_cache_alloc_node_noprof(struct kmem_cache *s, gfp_t flags,
> @@ -679,7 +679,7 @@ static __always_inline __alloc_size(1) void *kmalloc_node_noprof(size_t size, gf
>  				kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
>  				flags, node, size);
>  	}
> -	return __kmalloc_node_noprof(size, flags, node);
> +	return __kmalloc_node_noprof(NULL, size, flags, node);

This is not ideal as now every kmalloc_node() callsite will now have to add
the NULL parameter even if this is not enabled. Could the new parameter be
only added depending on the respective config?

>  }
>  #define kmalloc_node(...)			alloc_hooks(kmalloc_node_noprof(__VA_ARGS__))